1. Technical Field
The present invention relates to image forming apparatuses.
2. Related Art
Image forming apparatuses such as laser beam printers are well known. Such an image forming apparatus includes for example a photoconductor, which is an example of a rotatable image bearing member for bearing a latent image, a developing device for developing the latent image borne on the photoconductor with developer at a developing location, a rotatable intermediate transfer member serving as an intermediate transfer member when transferring the developer on the photoconductor to a medium to form the image, a voltage supply section supplying to the intermediate transfer member a transfer voltage for letting the developer on the photoconductor advance to the intermediate transfer member at a primary transfer location, and a secondary transfer member for transferring the developer that has moved to a secondary transfer location through rotation of the intermediate transfer member to the medium. The image forming apparatus further includes a removal member that is arranged on a downstream side, with respect to the rotation direction of the intermediate transfer member, from the secondary transfer location, and that removes remaining developer remaining on the intermediate transfer member by abutting against the intermediate transfer member.
When the image forming apparatus receives an image signal or the like from an external device, such as a host computer, the latent image borne by the photoconductor is developed with the developer in the developing device. Then, the developer on the photoconductor is transferred by primary transfer, such that it is attracted to the intermediate transfer member to which a transfer voltage is supplied with a voltage supply section, and then it is transferred by secondary transfer to a medium at a secondary transfer location. Then, the developer, which has been transferred by secondary transfer to the medium, is fixed to the medium with a fixing device, and the image is finally formed on the medium. On the other hand, the developer remaining on the intermediate transfer member without being transferred to the medium by the secondary transfer member is removed with the removal member.
Now, while carrying out the image forming operation, a situation may occur in which the image forming operation is stopped midway. An example of such a situation is a situation in which the medium becomes stuck while being transported in the image forming apparatus during the image forming operation (the medium becoming stuck is referred to as “jamming” in the following). In this case, the developer remaining on the intermediate transfer member is removed with the removal member after the operator has resolved the jamming by removing the medium that has become stuck in the image forming apparatus in order to resume the image forming operation.
When such a situation (jamming of the medium or the like) stopping the image forming operation midway has occurred, remaining developer may be located upstream, with respect to the rotation direction of the intermediate transfer member, from the secondary transfer location, between the primary transfer location and the secondary transfer location. In this case, the amount of remaining developer to be removed by the removal member tends to become large, since the remaining developer is removed by the removal member in order to resume the image forming operation.
Moreover, when the transfer voltage for letting the developer advance to the intermediate transfer member is supplied to the intermediate transfer member while a large amount of the remaining developer is removed by the removal member in order to resume the image forming operation (conventionally, the transfer voltage was supplied to the intermediate transfer belt while removing the remaining developer on the intermediate transfer member with the removal member after resolving the jamming), then the large amount of remaining developer remaining on the intermediate transfer member is attracted to the intermediate transfer member. In this situation, there is the risk that the remaining developer will remain on the intermediate transfer member without being suitably removed by the removal member.
Moreover, the following two aspects are desirable regarding the remaining developer remaining on the photoconductor and the intermediate transfer member (also referred to simply as “remaining developer” in the following) when a situation has occurred in which the image forming operation is stopped midway (such as jamming of the medium).
Firstly, it is desirable that the developer remaining on the photoconductor is suitably transferred to the intermediate transfer member. This is because if the remaining developer is transferred to the intermediate transfer member, then the configuration of the image forming apparatus can be made simpler than if the remaining developer is removed on the photoconductor without being transferred to the intermediate transfer member.
Secondly, it is desirable that the developer remaining on the photoconductor or the intermediate transfer member is suitably removed by the removal member in order to resume the image forming operation. For example, if the transfer voltage for letting the developer advance to the intermediate transfer member is supplied to the intermediate transfer member while the remaining developer is removed with the removal member, the remaining developer is attracted to the intermediate transfer member. In this situation, there is the risk that the remaining developer will remain on the intermediate transfer member without being suitably removed by the removal member.
Moreover, in an image forming apparatus, the image quality of the image can be adjusted by forming an adjustment pattern on the intermediate transfer member from the viewpoint of preventing a decrease of the image quality of the image formed on the medium. This adjustment pattern is constituted by developer that has advanced from the photoconductor to the intermediate transfer member at the primary transfer location. The image forming apparatus is provided with pattern detection members for detecting the adjustment pattern (developer) and adjusts the image quality based on a detection result of the adjustment pattern provided by the pattern detection member.
Furthermore, the removal member abuts against the intermediate transfer member and removes the adjustment pattern (more specifically, the developer constituting the adjustment pattern) at the developer removal location after detecting it with the pattern adjustment member. The image forming apparatus then can suitably carry out the following image formation by removing the adjustment pattern (developer) on the intermediate transfer member with the removal member.
Now, the following two aspects are desired when forming the adjustment pattern on the intermediate transfer member and removing the developer constituting this adjustment pattern.
Firstly, it is desirable that the developer on the photoconductor is suitably transferred to the intermediate transfer member when forming the adjustment pattern. The reason for this is that when the developer is not suitably transferred to the intermediate transfer member, the density of the adjustment pattern will not be suitable and the adjustment of the image quality of the image cannot be carried out in a suitable manner.
Secondly, it is desirable that the developer constituting the adjustment pattern formed on the intermediate transfer member is suitably removed by the removal member. For example, if the transfer voltage for letting the developer advance to the intermediate transfer member is supplied to the intermediate transfer member while the developer is being removed with the removal member, then the developer constituting the adjustment pattern is attracted to the intermediate transfer member. In this situation, there is the risk that the developer will remain on the intermediate transfer member without being suitably removed by the removal member.
It should be noted that JP-A-2002-169389 and JP-A-2001-337507 are examples of related technology.